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Stargazing: Getting Started

Behold November’s Super-Duper Supermoon

You won't want to miss the biggest, brightest full Moon in more than 68 years. Find out what makes supermoon 2016 so special and how best to view it.

The Moon will be precisely full on Monday, November 14th at 13:52 UT, which occurs at dawn in the western half of the U.S. and Canada.Bob King

Get ready for the Moon to hit your eye like a big pizza pie on Sunday, November 13th. That night, skywatchers around the planet will witness the closest, brightest, and biggest full Moon since January 26, 1948 — the year the Cleveland Indians last won the World Series and the 200-inch Hale telescope on Mount Palomar was dedicated.

We'll all be crossing our fingers for clear skies, since the next such Moon won't occur until November 25, 2034. These bright, close full Moons are popularly called "supermoons," a wonderful description that makes people sit up and take notice.

The term supermoon is a recent invention. It came into common use in 2011, but appears to have been coined back in 1979 by Richard Nolle, who describes himself as a "certified, professional astrologer." His definition of a supermoon was generous: "... a new or full moon which occurs with the Moon at or near (within 90% of) its closest approach to Earth in a given orbit."

The Moon's eccentric elliptical orbit causes its distance from Earth to vary during each revolution. The nearest point is called perigee; the farthest, apogee. Not to scale.Bob King

Because the Moon's orbit is an ellipse instead of a circle, its distance from Earth varies during the month from about 225,800 miles (363,400 km) at perigee, or closest approach, to 252,000 miles (405,550 km) at apogee. Changing the distance causes the Moon's size and brightness to change as well. A perigee or supermoon is on average 7% bigger and 16% brighter than an average full Moon, but during an unusually close perigee, the full Moon can be 12–14% larger than a full Moon at apogee (sometimes called a micromoon) and 30% brighter.

Since we can only see one Moon in the sky, there's no way to directly compare macro and micro full Moons in real time, so you'll have to recall the appearance a typical full Moon and compare it to the upcoming supermoon 2016. Or hold the image of the November supermoon 2016 in your mind's eye and compare it to the next micromoon on June 8, 2017.

A comparison of the Moon at its closest to Earth (left) and farthest. The change in distance makes the full Moon look 14% larger at perigee than apogee. Laurent Laveder

How about a measuring device? Consider making what I'll call a Supermoon Sighter. With a pair of scissors, cut a series a slots of varying widths in an index card, then hold the card as best you can parallel to your face and at maximum arm length while facing the Moon. Close one eye and use the other to determine the slot into which the Moon fits snugly. Mark the date under that slot and its width in millimeters.

Make a simple Moon-measuring device by cutting slots of different widths in an index card. It's not hard science but will serve to measure larger differences in lunar diameter with the naked eye. Bob King

Follow exactly the same procedure during an apogee Moon and you should be able to see the size difference. It works best when the Moon is visible in twilight because the brighter sky background makes the slots easier to see. Of course, you can simply take photos of November's and next June's full Moons using the same telephoto or telescope settings and place them side-by-side as Laurent Laveder did in the photo above.

Several times each year, the full Moon occurs within a day or two of perigee, making supermoons somewhat common ... though not equal. The closer perigee and the moment of full Moon are to coinciding, the more exceptional the supermoon. Not only will November's full Moon occur at the closest perigee of the year, but the "stretchiness" of the lunar orbit will bring it in even closer.

These panels show the sky to the east at nightfall on the dates of the last, current, and future supermoons. Even though the Moon will be closest on November 14th, it's depicted on the 13th (center panel), when most North American observers will be out watching. The 1948 event found the Moon in the company of Mars and Saturn. During the next, the Moon will occult numerous Hyades star cluster stars and Aldebaran. Lunar distances are measured from the center of Earth to the center of the Moon.Maps: Bob King, Source: Stellarium

Sometimes the Moon's orbit is rounder, other times more elliptical, due to the ever-changing distances and relative positions of the Sun, Moon, and Earth, the inclination of the Moon's orbit, the non-spherical shape of the Earth, and even the gravitational attraction of the other planets. But the Sun's the biggest culprit — its gravitational attraction is more than twice as large as that between Moon and Earth. Add all these effects together, and the Moon's eccentricity (the amount by which the orbit deviates from a circle) varies from 0.026 to 0.077, or 5.5%. A circle has an eccentricity of 0.0.

When more oval, the Moon's perigee point gets unusually close to Earth, and if a full Moon arrives at that point, it will be considerably closer to us than during those times when the lunar orbit more closely resembles a circle. In a word, the Moon's perigee distance varies. Apogee too, naturally!

If a new or full Moon lies at the apogee or perigee point, the shape of the Moon's orbit can be slightly altered, resulting in a closer perigee than normal and an exceptional supermoon. A full Moon that occurs at the closest perigee of the year is said to be at proxigee. Not to scale. Bob King

Perigee and apogee distances also vary if a new or full Moon occurs at either point. Then all three bodies — Earth, Moon, and Sun — are in a straight line and exert their greatest gravitational attraction on one another. Earth and Sun in effect tug the Moon a little bit closer yet. And if this alignment happens within a few months of the Earth being closest to the Sun, when the Moon feels the Sun's gravity strongest, our satellite can snug up even closer to us. And wouldn't you know, we're closest to our star from November through February.

All these conditions will be met on November 13-14 to make the supermoon 2016 the most amazing until 2034. To enhance your supermoon 2016 experience, I encourage you to catch the Moon at moonrise, when the Moon Illusion will be at work. This psychological trick our eyes and brain play on us makes the Moon appear much larger when viewed near the horizon than higher overhead. Click here to find out exactly when the Moon will rise for your location.

Share November's supermoon 2016 with friends and family. The Moon will make its grandest impression at moonrise November 13th and before moonset the following morning for the Americas. Click the image to find out when the Moon rises for your town.Göran Strand / astrofotografen.se

For much North America, the supermoon 2016 will be closest and brightest during the overnight hours of November 13–14 — Sunday night and Monday morning until moonset. The moment of maximum supermoonness occurs at 11:23 UT (6:23 a.m. EST) Monday morning, November 14th, so everyone across the Americas will have the chance to see the Moon when it's at its closest, although it will be minutes before setting if you live on the East Coast. At that time, the distance between Earth and Moon will shrink to a mere 221,524 miles (356,509 km) or 1.2 light-seconds. Compare this to the average distance of 238,900 miles (384,472 km), a tenth of a light-second farther off.

Bear in mind, that the supermoon 2016's closest approach to Earth occurs 2½ hours before it's technically full, so observers in the Eastern states will see an ever-so-slightly-less-than-full Moon. Those living in the western half of the U.S., including Alaska and Hawaii, will get to experience both the "special moment" and the Moon at maximum fullness in either a twilight or dark sky. In the eastern hemisphere, including Europe and Africa, the Moon will be a little closer on the evening of Monday November 14th. Times are included below so you can explore your inner lunatic:

Moon closest to Earth on November 14th at 11:23 UT (Greenwich Time) or Monday morning November 14th at:

6:23 a.m. Eastern Standard Time

5:23 a.m. Central

4:23 a.m. Mountain

3:23 a.m. Pacific

2:23 a.m. Alaska

1:23 a.m. Hawaii

Moment of maximum full Moon occurs on November 14th at 13:52 UT or Monday morning November 14th at:

8:52 a.m. Eastern

7:52 a.m. Central

6:52 a.m. Mountain

5:52 a.m. Pacific

4:42 a.m. Alaska

3:32 a.m. Hawaii

Cloudy skies on the big night? Click over to the Virtual Telescope Project for a live view.Gianluca Masi

If the weather's bad from your town on both the 13th and 14th, you can fall back on the Web. Italian astronomer Gianluca Masi will live stream the joy of the giant Moon on his Virtual Telescope Project starting at 16:00 UT (11 a.m. Eastern) November 14th. You can also watch it live on Slooh's Facebook page where they're calling it the Mega Beaver Moon. 'Beaver' refers to the November moon's traditional name. In November, the early colonists and Algonquin tribes set beaver traps before the swamps froze to ensure a good supply of warm furs for the coming winter.

Tides are always higher at new and full Moons due to the alignment of Sun, Earth, and Moon, but an extra-close Moon will also mean higher tides than normal. If you live along a coast line, watch for these on November 14th and several days after.

Quite wonderful, isn't it, that so many small gravitational influences can add up to produce such a singular event. It makes us feel connected to the cosmos in a very real way. Clear skies!

About Bob King

Amateur astronomer since childhood and long-time member
of the American Association of Variable Star Observers (AAVSO), Bob King also teaches community education astronomy and writes the blog Astro Bob. The universe
invites us on an adventure every single night. All we need do is look
up. My book "Night Sky with the Naked Eye" was just published and is now available on Amazon and BN. It covers all the great things you can see at night with just your eyeballs. No equipment needed!

21 thoughts on “Behold November’s Super-Duper Supermoon”

This is not the brightest Full Moon of this year. That’s because this month’s Full Moon passes widely south of Earth’s shadow, and does not reflect as much light toward us as it would if the Moon narrowly missed the shadow. The sharp brightening of the Moon or an asteroid when it appears almost exactly 180 degrees from the Sun is sometimes called “the opposition effect, or opposition surge.”

Robert,
Thank you for writing. I agree the opposition surge would be less because the alignment is off, but wouldn’t the increased brightness due to decreased distance be more than enough to compensate? Is there a way to compare brightness/close perigee vs. a decrease in the opposition effect with numbers?

difference can be 40% between 4° and 0°. In principle the effect would be large enough to offset 30% the distance effect so that a near-ecliptic full Moon at apogee could be brighter than an off-angle supermoon (this weeks angle > 5°).

However the article is behind paywall so I don’t know exact curve. It is likely the sharpest rise is close to 0° where we never benefit from it since that is in effect a lunar eclipse (the article mentioned uses data taken from Clemetine lunar orbiter). For best results wait for supermoon near ecliptic 🙂

Also when such small angles have an effect there would only be a short time window to see the brightest possible Moon and it depends on the observer location on Earth too (up to +/- 1 ° degree different viewing angle of the Moon depending on where you are).

Or the article (which I can’t find) that said this: The Sun, though very bright, covers an incredibly small part of the sky. If you make a circle with thumb and forefinger and hold it out at arm’s length, the size of the circle that just surrounds the Sun is the size of a pea. You can try this safely at night with the full Moon, since the Sun and the Moon have the same apparent size in the sky. Most people guess that the Moon might be the size of a Ping-Pong ball, but it is much, much smaller.

GH,
I originally was looking for a paper punch to test out but couldn’t find one around the house. I also tried out a couple of different straws, but they didn’t work because of focusing, refractive and reflection problems. Then the idea of slots came to mind. If you could punch many different sized holes, that would be really nice.

Every article I have yet seen written on this topic by over-zealous astronomy enthusiasts ends up gored by the moon’s horns. I know you folks sincerely want to generate some good “science joy” by riding the stupid train of the supermoon, but come on. It never works!

Bob, let’s start with your index card measuring apparatus. You write: “It’s not hard science but will serve to measure larger differences in lunar diameter with the naked eye.”

No. It’s not hard science. This is a crude method of measuring angles (not useless, but crude) that cannot reliably measure anything as slight as the difference between perigee and apogee, mainly because the distance between the fingers at the end of your out-stretched arm and your eyes VARY significantly with altitude above the horizon. When you’re looking level, a gap with a diameter of 0.25 inches (or the spacing between the lines on a common 3×5 US index card) has an angular size equal to 34 minutes of arc when held out in front of you (assuming a typical distance of 25 inches: minutes=3438*gap/armlength). But this is increased substantially when you’re looking “up” since your shoulder is below your eyes. Then a quarter-inch gap has an angular size of 45 minutes of arc. That difference is approximately twice the difference between apogee and perigee moon diameters which implies that the index card measurer can only be used when the Moon is at some fixed altitude. Otherwise, any real change is swamped. Also looking at your example here, you’ve made gaps of 23, 11, 26, 21, and 16 minutes of arc which is a much greater range than you could ever expect to see in the Moon size. That image ITSELF pushes bad science. It suggests a range of sizes far greater than the Moon’s actual size change.

You note that the Moon will be brighter, and this has become one of the big “at least this is true” footnotes in articles that try to make lemonade from this lemon of an Internet fantasy. Surely if the Moon is “30 percent” brighter, that’s easy to see, right? But as it happens, it’s barely visible even for skilled observers. A 30% increase in brightness corresponds to about 0.3 magnitudes (a mathematical coincidence) and that’s right at the limit of what good observers can detect when they have comparison objects. This is not a normally observable difference in brightness. Further, this 0.3 magnitude change in brightness is the same as what the Moon’s apparent brightness displays thanks to changing extinction as it climbs from 16 to 24 degrees above the horizon and again as it climbs from 24 to 45 degrees above the horizon. Have you ever said to yourself that the Moon looks so much brighter at 45 degrees than it did at 24 degrees?? This change is identical to the change in the Moon’s brightness from apogee to perigee. It’s insignificant.

Finally, regarding the tides, contrary to popular astronomy lore, the Spring tides occur about a day AFTER Full Moon or New Moon in most places on the Earth and in other places even later. In many ports in northwest Europe, the Spring tides occur two to three days after the syzygy alignment (the straight line of New/Full Moon). So to see the maximum effect of perigee on the tides, you typically want the perigee to fall a day or two after Full/New Moon. Highest tidal ranges and supermoons don’t match. There will, of course, be significant large tidal ranges early next week, as there are right after any syzygy, twice a month. They will be a little higher still, thanks to perigee. Perigee in included in the standard calculations, and it’s only one of many features in the tidal harmonic behavior at most locations.

Since a near Moon moves faster, does it appear Full for a shorter period of time? (And a far Moon for longer?)

Though theoretical “Full Moon” may be very brief, the Moon usually appears Full to us for more than one day. Since the Moon is moving fastest at perigee, is this duration shortened? And lengthened at apogee? (The Moon’s speed varies in both linear speed and — more relevant for this question — apparent angular speed. It’s ‘area speed’ is constant — one of Kepler’s wonderful discoveries.)

Some related questions:

To what degree can we perceive changes in any of the following:

– The apparent size of the Moon (at various phases or positions)?

– The apparent brightness of the Moon?

– The apparent duration of a phase? (How ‘long’ is a Full, Half or New Moon?)

– The apparent angular speed of the Moon. (Even if we can’t see this directly, can we perceive a change in the duration of apparent fullness? Or in the speed of passage between neighboring stars, or through a constellation?)

– The same phenomena for other planets, including (except for fullness), the Sun?

Who has previously observed or investigated these phenomena? (Hipparchus apparently noticed that the Moon appears larger at certain times of the month, and reasoned that this was due to its being closer. And the variation in the angular movement of both Moon and Sun was known in ancient Babylonia. Who has noticed more recently?)

Joe,
Good questions. Yes, the Moon is moving fastest at perigee and so moves through full phase more rapidly. In other words, it makes the transition from waxing to waning moon more swiftly.
Related to this is your question about how soon after (or before) full phase we can detect that the moon isn’t “full.” I think that varies person to person depending on closely you look at the moon. It’s relatively easy to detect the day before and after. How many hours before? I’ve never tested myself on this so can’t say.
You can see a size difference with the naked eye between a perigee and apogee moon, again, if you’re paying close attention. You can also try out the simple slotted card method I wrote about to see if you can see that difference yourself.
Whether the perigee Moon appears brighter depends on your personal perception, the clarity of the atmosphere and the height of the moon at the time of observation. One could detect the difference photographically by taking pictures of both apogee and perigee moons at identical altitudes under the same atmospheric conditions (hazeless, cloud-free skies).
You can perceive the change in speed of Moon by measuring how many degrees it moves to the east in its orbit at perigee and then at apogee. The difference is noticeable especially when comparing how long it takes the Moon to cover and uncover stars during occultations.
Planets are always changing speed depending where they are in relation to the Earth and their distance from the Sun. Likewise the Sun – it also APPEARS to change speed depending on how far the Earth is from the Sun. We’re closest in Jan. (Sun appears to move faster) and farthest in July (a slower-moving Sun).

I would like to add that this was not only the closest full moon since 26 January 1948 and until 25 November 2034 but even the closest moon at all. I checked a list of the lunar perigee distances for several decades around 2016 and noticed that per year there are two minima of the lunar perigee distance: one occurs near full moon and the other one near new moon.

Sorry… rained out literally all week down here at 46 South, so NO SuperMoon (this time)!
Have seen quite a few previously in the last 50 years or so, so not too disappointed.

Then, we had that rather destructive 7.8 quake down here in NZ last Monday week… still strong aftershocks, a 5.7 and 5.4 this week, amongst nearly 6,000 aftershocks. And the SuperMoon had nothing to do with it, whatsoever, and it did NOT cause the recent 7.3 Fukashima quake either. A few skyscraper buildings in our Capital are being dropped to the ground (too trashed to repair) and dozens more are still evacuated. Lived there for 30 years and was closely involved in Civil Defence and LandSAR work 3 years ago, when the Seddon fault did a 6.5… so it feels personal. This time, only 2 folk died versus over 250 at Napier, NZ, in 1931 with it’s own 7.8… phew. We Kiwis are dusting ourselves off, and simply carrying on with our lives down here in the “shaky isles”. Good luck for the San Andreas fault in California!!!

Bob.. looking on Seiichi Yoshida’s website today, I see 3 comets within a few degrees of each other… a nice triple-whammy for your readers, out there.

They are as follows… 45p/ H-M-P (an old fave od mine), 9p, and good old 29p. They are all at Solar Elongation 40 -45 deg and best seen on the near meridian ~ 8 -9pm local time, in the early evening sky.

29p the other night was below mid 13th Mv in the 30cm loaned dielectric scope at 400x.
No reported visual obs of 45p yet, on LIADA/ BAA, but it could reach 11 or 12th Mv at Xmas. 9p Tempel I has faded out beyond 14th Mv and might have to be visually abandoned. Your 15 incher just might be able to bag all three this week.

Nice article. I like your makeshift angular size measurement device, aka – index card with slots cut into it. Have you tried using this to compare the angular size of the Moon near the horizon and when it is overhead on a given night, as a way to demonstrate the Moon Illusion? I think I’m going to incorporate this “tool” in the lunar observing portion of my astronomy class if you don’t mind.

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